WO1999056458A1

WO1999056458A1 - Method for measuring image noise of image reader, resolution measuring apparatus and resolution measuring method, and recording medium therefor

Info

Publication number: WO1999056458A1
Application number: PCT/JP1999/002241
Authority: WO
Inventors: Keiji Honda; Syuu Nitta; Masahide Hashimoto
Original assignee: Pfu Limited
Priority date: 1998-04-27
Filing date: 1999-04-27
Publication date: 1999-11-04
Also published as: CN1273737A; CN1516479A; EP0998113A1; TW472481B; EP0998113A4; TW471230B

Abstract

According to a method for measuring image noise of an image reader of the invention, image data collected by reading a measurement area having a uniform density of a test chart is analyzed by an image analyzing program of a computer, an abnormal part of the image data is extracted, and it is judged whether or not the abnormal part is noise based on predetermined criteria. According to a method for measuring the resolution of an image reader of the invention, a test chart prepared by slightly shifting the pitch of a black-and-white line pair pattern from the pixel pitch of the image reader is read in such a way that there is always a portion where the pattern coincides with a pixel, only a necessary portion of the read image data is segmented, the gradation difference is calculated for each pixel of the whole segmented image data, the maximum gradation difference is found, and if the maximum gradation difference exceeds an acceptance/rejection judging value, a resolution test acceptance is given.

Description

TECHNICAL FIELD The present invention relates to an image noise measuring method for an image reading device, a resolution measuring device, a resolution measuring method, and a recording medium therefor.

The present invention relates to a method of measuring image noise and a method of measuring resolution of an image reading device, and a recording medium thereof, and more particularly to a method of quantitatively measuring image noise of an image reading device connected to a host device and providing image data to the host device. Image noise measurement method to determine the quality based on predetermined criteria, and a resolution measurement method that enables automatic computer processing of a resolution test in which one pixel of a CCD element resolves one bar, and their recording media About. Background art

Noise of an image read by an image reading device connected to the host device and providing the image data to the host device causes a decrease in image quality, and causes a deterioration in reproducibility of the document. It is important to remove the noise in order to stabilize the performance of the image reading device. Therefore, to accurately measure the noise generated in the image reading device is to grasp the actual state of the image reading device, and at the same time, is an essential element for eliminating the cause.

Taking a transparent original as an example, the relationship between the original density and the output of the CCD element due to the light transmitted through the original does not change linearly, but changes exponentially as shown in Fig. 23. It is known. This indicates that the noise generated in the output by the CCD element varies in the degree of the effect depending on the document density. Therefore, it can be seen that the noise generated can be reliably captured by reading a plurality of originals with different densities when actually measuring noise with a specific original.

With reference to FIG. 24, a case will be described in which, for example, dust or the like is mixed in the image reading apparatus, and the light detection of a specific CCD element is abnormal.

As shown in Fig. 24 (a), the image of the abnormal CCD element The data shows a prominent value, and when an original composed of uniform density is read as shown in Fig. 24 (b), image data dropout occurs at the location of the abnormal CCD element. It appears as vertical stripes (in the figure, a set of horizontal white dots). Referring to FIGS. 25 and 26, a processing flow for measuring noise in a test process of an image reading apparatus according to a conventional technique will be described. In particular, FIG. 25 shows a block diagram, and FIG. 26 shows a flowchart for measuring noise.

In FIG. 25, in the image reading apparatus 12 on which the test chart 11 is placed, the light emitted from the light source lamp 22 passes through the test chart 11 and the CCD element 23 passes through the test chart 11 It emits an electrical signal in response to the light. As the test chart 11, a test chart 1 having a plurality of reading areas 1a, 1b, 1c, and 1d as shown in FIG. 1 is applied. Further, the reading moving section 24 moves the reading section including the CCD element 23 to execute reading in the sub-scanning direction. Further, the arithmetic control unit 21 amplifies the electric signal emitted from the CCD element 23 into an appropriate form, converts it into image data, and transfers the image data to the measuring device 15. The driver program 52 of the measuring device 15 that has received the image data from the image reading device 12 transfers the image data to an arithmetic control unit 51, displays the image data on a display unit 55, and performs the measurement. Prepare for visual inspection of the operator of device 15

In FIG. 26, in step S201, the operator places the test chart 11 on the image reading device 12 to be tested, and proceeds to step S202 to read the image reading device 1 2 Then, the test chart 11 is read, and the image data is transferred to the measuring device 15 in step S203. The measuring device 15 that has received the image data in step S204 proceeds to step S205, displays the image data on the display unit 55, and performs a visual check in step S206. In step S207, if the found noise is within the specified allowable range, the process proceeds to step S209, where it is determined that there is no noise, and the image reading device 12 is determined as a device that does not need to be modified. Deliver to the process. If the detected noise exceeds the specified allowable range, the process proceeds to step S208, where it is determined that there is noise, and the image reading device 12 is determined as a device requiring rework. Hand over to the rework process. In step S210, the corresponding test result data is stored in the recording unit 56, and the noise measurement process ends. Such a noise measuring method in the test process of the image reading apparatus 12 according to the conventional technique has the following problems.

The extraction and measurement of the image noise and the determination of the pass / fail of the image are executed by the operator visually checking the read image of the test chart 11 displayed on the display unit 55 of the measuring device 15. That is, the noise measurement method in the test process relies on the sensitivity test by the person in charge. Therefore, the level of proficiency of the person in charge greatly affects the test results, and the personal condition of the person in charge, such as eyesight, as well as the health condition of the day and other factors affect the test results. It is difficult to do.

On the other hand, one closely related to the image noise described above is the resolution of the image reading device. The resolution of an image reading device indicates how finely it can be identified, and is determined by the lens and CCD provided in the device. For this reason, the resolution can be increased by using multiple lenses, enlarging the image, and then reading the image with CCD.

FIG. 29 shows a test chart for a resolution test generally used when evaluating the resolution of an optical component or an optical system. In Fig. 29 (a), the test chart shows the combination of three bars provided in both the vertical and horizontal directions and the two spaces separating them as groups of ^, and the pattern size is reduced in order. Meanwhile, they are arranged regularly from outside to inside.

To check the resolution of the image reading device, the test chart shown in FIG. 29 (a) may be read by the image reading device to be tested, and the image obtained from the image reading device may be confirmed. That is, the resolution can be determined from the size of the smallest pattern in which three bars can be identified. Note that, for example, if the image reading device has a resolution of 240 dpi as a basic specification as a resolution specification of the image reading device, according to the test chart shown in FIG. Approximately 1 1 / m of bar — identification is required.

FIG. 27 shows a configuration diagram of the prior art. In FIG. 27, to perform a resolution test of the image reading device 12, the test chart 71 shown in FIG. 29, the image reading device 12 to be tested, and the measuring device 16 are used. Be composed. Note that the image reading device 12 is operated by the arithmetic control unit 21 based on the instruction from the measuring device 16 so that the light source lamps 22 and It controls the operations of the CCD element 23 and the reading movement section 24 and transfers the read image data of the test chart 71 to the measuring device 16. The measurement device 16 is controlled by the arithmetic and control unit 61 and exchanges data with the image reading device 12 via the driver program 62. The received image data is processed by the arithmetic and control unit 61 and the display unit 6 The read image is enlarged and displayed on 6. The determination of the quality of the resolution is performed by visually checking the image displayed on the display unit 66. The data of the test results are stored in the storage unit 67.

The processing procedure of the prior art will be described with reference to FIG. The same reference numerals as those shown in Fig. 27 are used.

In step S301, the judge sets the test chart 71 at a predetermined position of the image reading device 12 to be tested and instructs reading. In step S302, the image reading device 12 starts reading the test chart 71 by driving the light source lamp 22, the CCD element 23, and the reading moving part 24, and in step S303. Then, the read image data is transferred to the measuring device 16. In step S304, the measuring device 16 receives the image data, processes the image data by the arithmetic control unit 61, and in step S305, displays the read image on the display unit 66 in an enlarged manner. In step S306, the judge visually checks the image displayed on the display unit 66. In step S307, the determiner determines whether the three bars can be identified in the image displayed on the display unit 66. If the three bars cannot be identified, in step S308, the image reading device 12 is determined to be defective because it does not have the resolution of the basic specification. If the three bars can be identified, in step S309, the image reading device 12 is determined to be non-defective as having the resolution of the basic specification. In step S310, the data of the measurement result is recorded in the storage unit 67, and the process ends.

As described above, as a method of checking the resolution, for example, a resolution test of the image reading apparatus 12 having the above-mentioned resolution of 240 dpi as a basic specification is performed by a skilled technician by, for example, enlarging and displaying a read image. It is judged by. For this reason, taking the example of a test using a general-purpose test chart shown in Fig. 29, which is generally known, the human judgment intervenes at the most important point where it looks first and invisible. Second, the person making the decision requires a wealth of experience and sensitivity to identify the image. The third problem is that the data remaining as test results is scarce. These are major weaknesses in both the production system and the quality assurance system of the image reading device 12.

In order to build an efficient production system for the image readers 12, it is desirable to implement a resolution test by computer processing. In order to be able to identify black and white bars, it is necessary that both the black bar and the space that separates it are visible. The contrast difference is very important. If the contrast difference is large, the bars and spaces can be clearly distinguished, and if the contrast difference is small, it is difficult to distinguish them. From these, computer processing can be realized by focusing on this contrast difference and relating human sensation.

The image reading device 12 forms reflected light from the original or transmitted light from the original on a CCD line sensor (23), converts the image into an electric signal, and performs internal processing. Therefore, the relationship between the original (71) image formed on the CCD line sensor and the size of the CCD light receiving section greatly affects the contrast difference. Some cases are illustrated by FIG. FIG. 30 (a) shows a case where the balance between the size of the pattern and the CCD element and the positional relationship between the pattern and the CCD element are both good and the contrast difference is large. Fig. 30 (b) shows the case of the The positional relationship between the turn and the CCD element is good, but the balance between the pattern and the size of one pixel of the CCD element is lost due to defocus, and the contrast difference is small. Further, FIG. The figure shows the case where the balance between the turn and the size of one pixel of the CCD element is good, but the positional relationship between the pattern and the CCD element is shifted, and the contrast difference is small.

By the way, the purpose of the resolution test is to extract the case shown in Fig. 30 (b) and determine that it is defective. However, measuring the contrast difference alone makes it difficult to distinguish the case shown in Fig. 30 (c). In addition, it is impossible to manage the positional relationship between the optical unit and the test chart in units of // m, and it is impossible to fix the positional relationship in all devices. Therefore, it is rare that the state of the case shown in FIG. 30 (a) can be created, and it is predicted that almost all of the cases will be close to the case shown in FIG. 30 (c). Therefore, the CCD element In determining the resolution at which one pixel resolves one bar, it is necessary to match the position of the pixel and the bar, so the judge must shift the position of the test chart slightly, and The judgment is made while excluding such factors.

Such an image resolution measuring method in the image reading apparatus 12 according to the related art has the following problems.

First, in the determination of the resolution at which one pixel of a CCD element resolves one bar, the versatility of the general-purpose test chart 71 significantly deteriorates the setability, making it impossible to establish an efficient production system. Second, when a resolution test is implemented by computer processing, the pattern and CCD element pixel size balance is broken due to defocus, etc., and the contrast difference is small, and the positional relationship between the pattern and CCD element. Cannot be distinguished from the case where the contrast difference is small.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image noise measuring method for an image reading apparatus that uniquely determines the presence or absence of image noise.

Another object of the present invention is to provide a recording medium storing a program for providing an image noise measuring method of an image reading apparatus for uniquely determining the presence or absence of image noise.

Another object of the present invention is to provide a resolution measuring device of an image reading device that can freely set the position of a test chart.

Another object of the present invention is to provide a method for measuring the resolution of an image reading apparatus that allows the position of a test chart to be set freely.

It is another object of the present invention to provide a recording medium storing a program for providing a method for measuring the resolution of an image reading apparatus capable of freely setting the position of a test chart. Disclosure of the invention

An image noise measuring method of an image reading apparatus according to one embodiment of the present invention is a method of causing an image reading apparatus to read a test chart having a reading area with a uniform density and collect and analyze image data. If the degree of variation of each image exceeds a predetermined range, the image reading apparatus determines that the image has image noise. According to this image noise measurement method, the presence or absence of image noise can be uniquely determined by analyzing the image data obtained by reading the read area with a uniform density of the test chart.

In another embodiment of the present invention, a method for measuring an image noise of an image reading apparatus includes a step of causing an image reading apparatus to read a test chart having a reading area with a uniform density and collect and analyze image data. If the average output value in the vertical or horizontal direction at a specific position deviates from the average value in the entire area beyond a predetermined range, it is determined that there is image noise at the position.

According to this image noise measuring method, it is possible to analyze image data obtained by reading a reading area with a uniform density of a test chart, uniquely determine the occurrence of image noise, and know the position of occurrence.

Further, in another embodiment of the present invention, a method for measuring an image noise of an image reading apparatus includes the steps of: causing an image reading apparatus to read a test chart having a reading area with a uniform density to collect image data; If the difference between the average output value in the vertical or horizontal direction at a specific position and its adjacent average output value exceeds a predetermined range, it is determined that there is image noise at that location. .

According to this image noise measuring method, it is possible to analyze the image data obtained by reading the read area with a uniform density of the test chart, uniquely determine the occurrence of image noise, and know the position of the occurrence.

The method for measuring the resolution of the image reading apparatus according to one embodiment of the present invention includes a case where the contrast difference is small as a result of the balance between the pattern and the size of one pixel of the CCD element being lost due to a defocus or the like. The case where the contrast difference is small as a result of the positional relationship of the CCD elements being shifted is identified.

Further, a method for measuring the resolution of an image reading apparatus according to another embodiment of the present invention includes a test in which a pattern in a document image formed on a CCD element is set to a value slightly shifted from a logical value. Use a chart and make sure that the white pattern and read pixel, and the black pattern and read pixel always match at regular intervals. Using this test chart, a sufficient area is read so that the pattern and the pixel always match, the gradation difference is calculated for each pixel of the read image of the entire area, and the maximum gradation difference is calculated. Is detected. If the maximum gradation difference exceeds the pass / fail judgment value, the resolution test is passed.

According to this resolution measuring method, the contrast difference between adjacent pixels in the reading area changes with a constant period. Therefore, even when the test chart is mounted on the image reading device, there is a portion where the pattern and the pixel always match without regard to the position of the test chart. For this reason, only by examining the maximum contrast difference, it is possible to identify a case where the balance between the pattern and the size of one pixel of the CCD element is lost due to reasons such as defocus and the contrast difference is small. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an explanatory diagram of a test chart according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a direction of a noise line according to the present invention. FIG. 3 is a block diagram according to the present invention. FIG. 4 is a flowchart according to a representative embodiment of the present invention. FIG. 5 is a flowchart according to a representative embodiment of the present invention. FIG. 6 is a flowchart according to a representative embodiment of the present invention. FIG. 7 is a flowchart according to a representative embodiment of the present invention. FIG. 8 is a flowchart according to a representative embodiment of the present invention. FIG. 9 is another configuration diagram of the present invention. FIG. 10 is a schematic flowchart of the present invention. FIG. 11 is a configuration diagram of an embodiment of the present invention. FIG. 12 is an explanatory diagram of an embodiment of the present invention. FIG. 13 is an explanatory diagram of an embodiment of the present invention. FIG. 14 is an explanatory diagram of an embodiment of the present invention. FIG. 15 is an explanatory diagram of an embodiment of the present invention. FIG. 16 is a flowchart of an embodiment of the present invention. FIG. 17 is a flowchart of the embodiment of the present invention. FIG. 18 is a flowchart of the embodiment of the present invention. FIG. 19 is a flowchart of the embodiment of the present invention. FIG. 20 is a flowchart of an embodiment of the present invention. No. 2

FIG. 1 is a flowchart of an embodiment of the present invention. FIG. 22 is a flowchart of the embodiment of the present invention. FIG. 23 is an explanatory diagram showing the relationship between the image density of a document and the CCD output. FIG. 24 is an explanatory diagram of a reading screen due to an abnormality of an individual CCD element. FIG. 25 is a block diagram of a noise measurement according to the related art. No.

FIG. 26 is a flowchart of noise measurement according to a conventional technique. Figure 27 shows FIG. 2 is a configuration diagram of a conventional technique. FIG. 28 is a flowchart of the prior art. FIG. 29 is a test chart for a conventional resolution test. FIG. 30 is a diagram showing the relationship between the image of the conventional technology and the size of the CCD light receiving unit. BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment)

A typical embodiment of the present invention will be described with reference to FIGS. An image noise measuring method for an image reading apparatus, which is a typical embodiment of the present invention, is configured as follows to solve the above-mentioned problem.

The image noise measuring method of the image reading apparatus is to make the image reading apparatus read a single uniform density reading area or a plurality of uniform density reading areas of different density levels, and to obtain a total of the individual measurement areas. It is assumed that the standard deviation value of the optical density of the pixel is calculated, and when the standard deviation value exceeds a predetermined numerical value range, the image reading apparatus detects an image noise.

By adopting this form, an effect of providing a unique reference for detecting image noise in the image noise measuring method is obtained.

The image noise measuring method of the image reading apparatus is to make the image reading apparatus read a single uniform density reading area or a plurality of uniform density reading areas of different density levels, and individually read the individual measurement areas. The average density of each vertical line, which is the average value of the output sequentially read by the CCD element in the sub-scanning direction, is calculated, and the average density of a specific vertical line is calculated as the average density of each vertical line in the vicinity, or When the average density of the individual measurement areas deviates beyond the range of a predetermined numerical value with respect to the average density, the vertical line is determined to be a noise line, and image noise is detected in the image reading apparatus.

Further, the image noise measuring method of the image reading device is configured to cause the image reading device to read a single uniform density reading region or a plurality of uniform density reading regions of different density levels, and to perform the individual measurement region. The average density of each horizontal line, which is the average value of the output read in the main scanning direction, is calculated, and the average density of a specific horizontal line is calculated as the average density of each horizontal line in the vicinity or the average of the entire individual measurement area. To the concentration On the other hand, when the value deviates beyond a predetermined numerical range, the horizontal line is determined to be a noise line, and the image reading apparatus detects an image noise.

Alternatively, the image noise measuring method of the image reading apparatus includes the steps of causing the image reading apparatus to read a single uniform density reading area or a plurality of uniform density reading areas at different density levels, and perform the individual measurement. The average density of each vertical line, which is the average value of the output sequentially read by the individual CCD elements in the sub-scanning direction in the area, is calculated. It is assumed that the vertical line is determined to be a noise line when the value deviates beyond the predetermined numerical value range, and that the image reading apparatus detects image noise.

Alternatively, the image noise measuring method of the image reading apparatus comprises: causing the image reading apparatus to read a single uniform density reading area, a certain area, or a plurality of uniform density reading areas having different density levels; The average density of each horizontal line, which is the average value of the output read in the main scanning direction in each measurement area, is calculated, and the average density of a specific horizontal line is a predetermined value with respect to the average density of the adjacent horizontal line It is assumed that the horizontal line is determined to be a noise line when deviating beyond the range, and an image noise is detected by the image reading apparatus.

By adopting these forms, an effect of providing a unique reference for detecting image noise and a unique reference for designating a position where the image noise occurs in the image noise measurement method is obtained.

A recording medium storing a program of an image noise measuring method of the image reading device is connected to a host device, and the image reading device that provides image data to the host device. The image reading device reads a single uniform density reading area or a plurality of uniform density reading areas at different density levels, and calculates a standard deviation value of optical densities of all pixels in the individual measurement areas. And a program for executing, when the standard deviation value deviates beyond a predetermined numerical value range, the image reading apparatus to report that the image noise has been detected by the image reading apparatus. .

Alternatively, the recording medium reads a single uniform density reading area, a plurality of uniform density reading areas of different density levels, or a plurality of uniform density reading areas by the image reading apparatus. A procedure for calculating an average density for each vertical line, which is an average value of outputs sequentially read in the sub-scanning direction by individual CCD elements in the individual measurement areas; and If the average density of each neighboring vertical line or the average density of the entire individual measurement area deviates beyond a predetermined numerical range, the vertical line is determined to be a noise line, and the And a program for executing a procedure for reporting that image noise has been detected.

Alternatively, the recording medium may cause the image reading device to read a single uniform density reading area or a plurality of uniform density reading areas of different density levels, and read the individual measurement areas. Calculating the average density of each horizontal line, which is the average value of the output read in the main scanning direction, and calculating the average density of a specific horizontal line to the average density of the neighboring horizontal lines or the entire area of the individual measurement area. When the average density deviates beyond a predetermined numerical range, the vertical line is determined to be a noise line, and a procedure for reporting that image noise has been detected in the image reading apparatus is stored. .

Alternatively, the recording medium allows the image reading device to read a single uniform density reading area or a plurality of uniform density reading areas of different density levels, and to read individual CCD elements in the individual measurement areas. Calculates the average density of each vertical line, which is the average value of the output sequentially read in the sub-scanning direction, and the average density of a specific vertical line is determined in advance with respect to the average density of the adjacent vertical line. If the value deviates beyond the numerical range, the vertical line is determined to be a noise line, and a procedure for reporting that image noise has been detected in the image reading device is stored.

Alternatively, the recording medium allows the image reading device to read a single uniform density reading area or a plurality of uniform density reading areas of different density levels, and in the main scanning direction in the individual measurement areas. The procedure for calculating the average density of each horizontal line, which is the average value of the read output, and the case where the average density of a specific horizontal line deviates from the average density of its adjacent horizontal line beyond a predetermined numerical range And a program for executing the procedure of determining the vertical line as a noise line and reporting that the image reading apparatus has detected image noise. By adopting these modes, the measuring apparatus for testing the image reading apparatus has an effect of mounting a procedure for detecting image noise and a procedure for specifying a position where the image noise has occurred.

In this specification, the main scanning direction refers to the main scanning direction. Accordingly, image data obtained by one main scan is linear one-dimensional image data, and forms one horizontal line of image data. Usually, a plurality of CCD elements arranged side by side in the main scanning direction collectively read the image data in the main scanning direction, which is a horizontal line.

The sub-scanning direction is a scanning direction perpendicular to the main scanning direction, and the linear one-dimensional image data obtained by scanning in the main scanning direction is The two-dimensional planar image data is accumulated by scanning. Therefore, one of the CCD elements provided side by side in the main scanning direction in the image reading device forms one vertical line of image data along the sub scanning direction.

A representative embodiment according to the present invention will be specifically described with reference to FIGS.

Fig. 1 shows a typical example of a test chart used in the image noise measurement method. That is, the test chart 1 shown here is made of a colorless and transparent material that forms an image by transmitted light. This measure eliminates the uncertainties due to diffuse reflections that occur when using test charts that form images with reflected light.

The test chart 1 has a plurality of reading areas 1a, lb, lc, and Id, each of which has a uniform density with a stepwise different density. For example, the reading area 1a has no image density, the reading area 1d has an image density that completely blocks transmitted light, and the reading areas 1b and 1c have no image density. Each of the reading areas has a predetermined light transmittance based on an intermediate value between the reading areas 1a and 1d. FIG. 1 (a) shows an example of a test chart in which a horizontal reading area is set, and FIG. 1 (b) shows an example of a test chart in which a vertical reading area is set. Although shown, it is needless to say that a material having a uniform concentration with a single concentration throughout may be used as necessary. Referring to FIG. 2, a noise line generated when the test chart 1 is read will be described. As shown in Fig. 2 (a), if a vertical noise line 2a is seen in the reading area 1a of the test chart 1 read by the image reading device, it is possible that an abnormality has occurred in a specific CCD element or It is presumed that dust or the like adheres to the specific CCD element and its function is affected.

As shown in Fig. 2 (b), if a horizontal noise line 2b is seen in the reading area 1a of the test chart 1 read by the image reading device, the movement in the sub-scanning direction is caused by a defect in the feed mechanism. It is presumed that this was caused by fluctuations in the optical system or by blinking due to instability of the light source lamp.

An embodiment of the image noise measuring method according to the present invention will be described with reference to FIGS.

Figure 3 shows a block diagram. That is, the image reading device 12 used for the test irradiates the light emitted from the light source lamp 22 onto the test chart 1 placed on the image reading device 12, and transmits the transmitted light via the optical system to the CCD element 2. Image 3 The test chart 1 shown here is the same as the test chart 1 described above with reference to FIG. In addition, the reading moving unit 24 moves the optical system in the sub-scanning direction to form vertical image data. The image signal generated in the CCD element 23 is transferred to the measuring device 13 by the arithmetic and control unit 21. The measurement device 13 analyzes the image data transferred from the image reading device 12 by the built-in measurement control program 33 to determine the presence or absence of image noise. The determination result of the presence or absence of image noise is displayed on the display unit 35 and stored in the recording unit 36.

One embodiment of the image noise measuring method according to the present invention will be described with reference to the flowchart shown in FIG. The reference numerals used in each process are the same as those shown in FIG.

In step S001, the operator places the test chart 1 on the image reading device 12 to be tested, and proceeds to step SO02, where the test chart 1 is set by the image reading device 12. In step S003, the image data is transferred to the measuring device 13.

The measurement device 13 that has received the image data in step S004 Proceed to and specify the measurement target area (by the measurement control program 33). Here, for example, in step S006, the reading area 1a in the test chart 1 shown in FIG. 1 is designated, the data analysis unit 33a incorporated in the measurement control program 33 generates the individual image of the target area. Calculate the average value of the density values for each day, and calculate the standard deviation value based on the average value in the next step.

In step S07, the standard deviation value is compared with a predetermined value. If the difference value is equal to or smaller than a predetermined allowable range value, the flow advances to step S09 to determine that there is no image noise. If the difference value exceeds the predetermined allowable range value, the process proceeds to step S08, where it is determined that there is image noise, and the image reading device 12 is handed over to a predetermined repair section.

In step S0110, the measurement record of the standard deviation value and the like is stored in the recording unit 36, and the process proceeds to step S011, for example, to continuously read the test chart 1 shown in FIG. When measuring the image data relating to the area 1b, the process returns to step S005. In addition, when the analysis of the image data for all the areas to be measured in the test chart is completed, the measurement result is displayed on the display unit 35 in step SO 12 and notified to the operator to perform the measurement. End the process.

Therefore, the presence of image noise is uniquely determined without relying on the visual check of the worker in accordance with the processing flow of the image noise measurement shown in Fig. 4, and the data used for the measurement is stored. And can be reproduced when needed.

Another embodiment of the method for measuring image noise according to the present invention will be described with reference to the flowchart shown in FIG. The reference numerals used in each process are the same as those shown in FIG.

In step S022, the operator places the test chart 1 on the image reading device 12 to be tested, and proceeds to step S022, where the test chart 1 is read by the image reading device 12. The test chart 1 is read, and the image data is transferred to the measuring device 13 in step S023.

The measuring apparatus 13 that has received the image data in step S0 24 proceeds to step S0 25 to specify the measurement target area. Here, for example, the test chart shown in Fig. 1 Specify the read area 1a in G1.

In step S 0 26, the data analysis unit 33 a included in the measurement control program 33 calculates the average of the density values applied to the individual CCD elements of the image data of the vertical line output by the individual CCD elements in the target area. Then, the process proceeds to step S027 to calculate an average value over the entire area of the density values of all the image data of the target area.

In step S028, the average value of the density values applied to the individual CCD elements in the image data of the vertical lines output from the individual CCD elements calculated in step S026 is calculated. The difference value is calculated by comparing with the average value of the density values of all the image data of the target area calculated in 27.

Alternatively, the average value of the density values applied to the individual CCD elements of the vertical line image data output from the individual CCD elements calculated in step S026 and the CCD located at a position separated by a predetermined number The difference value is calculated by individually comparing the image data of the vertical lines output by the elements with the average value of the density values applied to the individual CCD elements. If it is determined in step S029 that the difference value obtained in step S028 is equal to or smaller than a predetermined allowable range value, the process proceeds to step S031, and it is determined that there is no image noise. If the difference value exceeds the predetermined allowable range, the process proceeds to step SO30, where it is determined that an image noise has occurred. The image reading device 12 is to be delivered.

In step S032, the measurement record such as the position of the vertical line by the CCD element where the abnormality was found is stored in the recording unit 36, and the process proceeds to step S033, for example, as shown in FIG. When measuring the image data of the reading area 1b in the test chart 1, the process returns to step S025. When the analysis of the image data for the entire region to be measured in the test chart 1 is completed, the process proceeds to step S034, where the measurement result is displayed on the display unit 35 and notified to the operator. Then, the measurement process ends.

Therefore, according to the processing flow of the image noise measurement shown in FIG. 5, the existence of the image noise and the position of the CCD element involved in the occurrence of the image noise are uniquely determined without relying on the visual check of the worker, Furthermore, the data used for the measurement can be saved and reproduced when needed. Another embodiment of the image noise measuring method according to the present invention will be described with reference to the flowchart shown in FIG. The reference numerals used in each process are the same as those shown in FIG.

In step S041, the operator places the test chart 1 on the image reading device 12 to be tested, and proceeds to step S042, where the operator reads the test chart 1 using the image reading device 12. The test chart 1 is read, and the image data is transferred to the measuring device 13 in step S043.

The measuring apparatus 13 that has received the image data in step S044 proceeds to step S045 to specify the measurement target area. Here, for example, the reading area 1a in the test chart 1 shown in FIG. 1 is designated.

In step S046, the data analysis unit 33a included in the measurement control program 33 calculates the average value of the density values of the image data of the individual horizontal lines constituting the main scanning direction in the target area. Then, the process proceeds to step S 047, and the entire area average value of the density values of all the image data of the target area is calculated.

In step S048, the average value of the density values of the individual horizontal lines constituting the main running direction calculated in step S046 and the target area calculated in step S047 are calculated. The difference value is calculated by comparing the average value of the density values of all image data with the average value individually.

Alternatively, the average value of the density values of the individual horizontal lines formed in the main scanning direction calculated in the step S 046 and the individual values formed in the main scanning direction at positions separated by a predetermined number of horizontal lines. Compare the average value of the density value of the horizontal line and calculate the difference value.

If it is determined in step S049 that the difference value obtained in step S048 is equal to or smaller than a predetermined allowable range value, the flow advances to step SO51 to determine that there is no image noise. If the difference value exceeds a predetermined allowable range value, the flow proceeds to step SO50, where it is determined that there is image noise. 2 shall be delivered.

In step S052, the measurement record such as the position of the horizontal line where the abnormality was found is stored in the recording unit 36, and the process proceeds to step S053. When measuring the image data corresponding to the reading area 1b in the yat 1, the flow returns to step S045. When the analysis of the image data for the entire area to be measured in the test chart 1 is completed, the process proceeds to step S 0 54 to display the measurement result on the display unit 35 and notify the operator. Then, the measurement step ends.

Therefore, according to the processing flow of the image noise measurement shown in FIG. 6, the existence of the image noise and the position in the sub-scanning direction where the image noise has occurred are uniquely determined without depending on the visual check of the worker. Further, the data used for the measurement can be stored and reproduced when necessary.

Another embodiment of the image noise measuring method according to the present invention will be described with reference to the flowchart shown in FIG. The reference numerals used in each process are the same as those shown in FIG.

In step S061, the operator places the test chart 1 on the image reading device 12 to be tested, and proceeds to step S062, where the operator reads the test chart 1 using the image reading device 12. The test chart 1 is read, and the image data is transferred to the measuring device 13 in step S063.

The measuring device 13 that has received the image data in step S064 proceeds to step S065 and specifies the measurement target area. Here, for example, the reading area 1a in the test chart 1 shown in FIG. 1 is designated.

In step S066, the data analysis unit 33a incorporated in the measurement control program 33 calculates the average of the density values applied to the individual CCD elements of the vertical line image data output by the individual CCD elements in the target area. Calculate the value.

In step S 067, the average value of the density values applied to the individual CCD elements of the image data of the vertical lines output from the individual CCD elements calculated in step S 066 described above is applied to the adjacent CCD elements. The difference value is calculated by comparing the density value with the average value.

If it is determined in step S068 that the difference value obtained in step S0670 is equal to or smaller than a predetermined allowable range value, the process proceeds to step S070 to determine that there is no image noise. If the difference value exceeds the predetermined allowable range value, the flow advances to step SO69 to determine that there is image noise, and to perform predetermined rework after completion of the test process. The image reading device 12 is to be delivered to the department.

In step S071, the measurement record such as the position of the vertical line by the CCD element in which the abnormality was found is stored in the recording unit 36, and the process proceeds to step S072. When measuring the image data over the reading area 1b in the chart 1, the process returns to step S065. When the analysis of the image data for the entire region to be measured in the test chart 1 is completed, the process proceeds to step S073, where the measurement result is notified to the operator and the measurement process is completed. Therefore, according to the processing flow of the image noise measurement shown in FIG. 7, the position of the CCD element involved in the existence of the image noise and the occurrence of the image noise is uniquely determined without relying on the visual check of the worker, Furthermore, the data used for the measurement can be stored and reproduced when necessary.

In step S081, the operator places the test chart 1 on the image reading device 12 to be tested, and proceeds to step S082, where the operator reads the test chart 1 using the image reading device 12. The test chart 1 is read, and the image data is transferred to the measuring device 13 in step S083.

The measuring apparatus 13 that has received the image data in step S084 proceeds to step S085, and specifies the measurement target area. Here, for example, the reading area 1a in the test chart 1 shown in FIG. 1 is designated.

In step S086, the data analysis unit 33a included in the measurement control program 33 calculates the average value of the density values of the image data of the individual horizontal lines constituting the target area in the main scanning direction.

In step S087, the average value of the density values of the individual horizontal lines configured in the main scanning direction calculated in step S086 and the density value of the individual horizontal lines configured in the adjacent main scanning direction The difference value is calculated by comparing with the average value of.

If it is determined in step S088 that the difference value obtained in step S087 is equal to or smaller than a predetermined allowable range value, the flow advances to step S0900 to determine that there is no image noise. Ma If the difference value exceeds a predetermined allowable range value, the process proceeds to step SO89, where it is determined that there is image noise. Shall be delivered.

In step S091, the measurement record such as the position of the horizontal line where the abnormality was found is stored in the recording unit 36, and the process proceeds to step S092. For example, the test chart 1 shown in FIG. When measuring the image data relating to the reading area 1b in step, return to step SO85. When the analysis of the image data for all the areas to be measured in the test chart is completed, the process proceeds to step S093, where the measurement result is notified to the operator, and the measurement process is completed.

Therefore, according to the processing flow of the image noise measurement shown in FIG. 8, the existence of the image noise and the position in the sub-scanning direction where the image noise has occurred are uniquely determined without relying on the visual check of the worker, Furthermore, the data used for the measurement can be saved and reproduced when needed.

According to the embodiment of the present invention described above, the following effects can be obtained.

The image reading device is caused to read a test chart having a plurality of reading regions having uniform densities based on individual densities set in steps, and to determine a standard deviation value of optical densities of all pixels in the individual measurement regions. Calculated, and when the standard deviation value deviates beyond a predetermined numerical range, it is assumed that image noise has been detected in the image reading apparatus.

By taking this measure, a unified calculation method for detecting image noise in the image noise measurement method and a unique judgment criterion are provided, so that reliable measurement of image noise can be performed without relying on visual checks of the operator. Can be executed. The image reading device is made to read a test chart having a plurality of reading areas of uniform density according to the individual densities set step by step, and the individual CCD elements are sequentially moved in the sub-scanning direction in the individual measurement areas. Calculate the average density of each vertical line, which is the average value of the read output, and calculate the average density of a specific vertical line with respect to the average density of each vertical line in the vicinity or the average density of the entire individual measurement area. If the value deviates beyond a predetermined numerical range, the vertical line is determined to be a noise line, and the image is read. It is assumed that an image noise is detected in the device.

Alternatively, the image reading device is caused to read a test chart provided with a plurality of reading areas having a uniform density based on individual densities set stepwise, and reading in the main scanning direction in the individual measurement areas. The average density of each horizontal line, which is the average value of the output, is calculated, and the average density of a specific horizontal line is a predetermined value for the average density of each horizontal line in the vicinity or the average density of the entire individual measurement area It is assumed that the horizontal line is determined to be a noise line when deviating beyond the range, and an image noise is detected by the image reading apparatus.

Alternatively, the image reading device is caused to read a test chart having a plurality of reading areas having a uniform density according to the individual densities set stepwise, and the individual CCD elements are set to be subordinate in the individual measurement areas. The average density of each vertical line, which is the average value of the output sequentially read in the scanning direction, is calculated, and the average density of a specific vertical line exceeds the predetermined value range for the average density of the adjacent vertical line. When deviating, the vertical line is determined to be a noise line, and image noise is detected by the image reading apparatus.

Alternatively, the image reading device is caused to read a test chart having a plurality of reading regions having uniform densities according to the individual densities set stepwise, and the output read in the main scanning direction in the individual measurement regions. The average density of each horizontal line, which is the average value of horizontal lines, is calculated.If the average density of a specific horizontal line deviates from the average density It is assumed that the line is determined to be a noise line, and that the image reading apparatus detects an image noise.

By taking these measures, a unified procedure for detecting image noise based on the image noise measurement method, a unique criterion, and a unique criterion for specifying the position where the image noise has occurred With this arrangement, it is possible to perform an effective measurement of the image noise without relying on the visual check of the worker.

In a measuring device for measuring image noise of an image reading device connected to a host device and providing image data to the host device, a plurality of uniform densities based on individual densities set stepwise are provided in the image reading device. A test chart having a reading area is read, and the standard deviation value of the optical density of all pixels in the individual measurement area is calculated. And a procedure for reporting that the image reading apparatus has detected image noise when the standard deviation value deviates beyond a predetermined numerical range.

Alternatively, the image reading device is caused to read a test chart having a plurality of reading areas having uniform densities based on individual densities set stepwise, and then moving to the individual measurement areas to read individual CCD elements. Calculating the average density of each vertical line, which is the average value of the output sequentially read in the sub-scanning direction, and calculating the average density of a specific vertical line, the average density of each vertical line in the vicinity, or the individual measurement. If the average density of the entire area deviates beyond a predetermined numerical range, the vertical line is determined to be a noise line, and a procedure for reporting that image noise has been detected by the image reading apparatus is executed. Store the program.

Alternatively, the image reading device is caused to read a test chart having a plurality of reading regions having a uniform density based on individual densities set step by step, and moving to the individual measurement regions in the main scanning direction. Calculating the average density of each horizontal line, which is the average value of the read output, and calculating the average density of a specific horizontal line to the average density of a nearby horizontal line or the average density of the entire individual measurement area. On the other hand, if the value deviates beyond a predetermined numerical range, the vertical line is determined to be a noise line, and a procedure for reporting that image noise has been detected in the image reading apparatus is stored.

Alternatively, by causing the image reading device to read a test chart having a plurality of reading areas having uniform densities based on individual densities set stepwise, the individual CCD elements are moved in the sub-scanning direction in the individual measurement areas. The procedure for calculating the average density for each vertical line, which is the average value of the output read sequentially, and the average density for each specific vertical line If it deviates beyond this, the vertical line is determined to be a noise line, and a procedure for reporting that image noise has been detected in the image reading device is stored.

Alternatively, by causing the image reading device to read a test chart having a plurality of reading areas with uniform densities based on individual densities set step by step, The procedure for calculating the horizontal density of each horizontal line, which is the average value of the output read in the main scanning direction in the measurement area, and the step of calculating the average density of a specific horizontal line from the average density of its adjacent horizontal lines If the value deviates beyond the range, the vertical line is determined to be a noise line, and a procedure for reporting that an image noise has been detected in the image reading device is stored.

By taking these means, the measuring apparatus for testing the image reading apparatus includes a procedure for detecting image noise and a procedure for specifying a position where the image noise has occurred. However, there is an effect that the work becomes versatile without being limited to a specific device.

(Second embodiment)

Another representative embodiment of the present invention will be described with reference to FIGS. 9 to 22. A resolution measuring device and a resolution measuring method for an image reading device according to another representative embodiment of the present invention are configured as follows to solve the above-mentioned problems.

As shown in another configuration diagram of the present invention in FIG. 9, the resolution measuring device 14a of the image reading device of the present invention shifts the black-and-white line pair pattern pitch a little from the reading pixel pitch of the image reading device. Create or create a black and white line pair pattern with a small amount of inclination, and the white pattern and read pixel, and the black pattern and read pixel match in the main scanning direction or sub-scanning direction at regular intervals of the resolution test. The reading means 3 reads the test chart 2 and the test chart 2, and the reading means 3 and the reading means 3 which read a sufficient width or a vertical area so that a pattern and a pixel always coincide with each other. Means 4 for cutting out only the necessary parts of the image data that has been extracted, and analysis for calculating the gradation difference for each pixel of the read image of the entire area of the cut out image data and detecting the maximum gradation difference And stage 5, if the maximum tone difference exceeds the quality determination value and a determination unit 6, the resolution test pass.

As shown in the schematic flow chart of the present invention in FIG. 10, the resolution measuring procedure of the resolution measuring device 14a having the above configuration is as follows. The entire area is read, and in step S102, the image data including the resolution and the image portion is cut out from the image data read by the cutout means 4 with a margin, and step S103 is performed. Indicates the range of the resolution pattern In step S104, the measurement target portion is cut out by the cutout means 4, and in step S105, every pixel of the read image of the entire area of the image data cut out by the analysis means 5 is extracted in step S105. The maximum tone difference is detected by calculating the tone difference, and in step S106, the judging means 6 judges whether the maximum tone difference exceeds the pass / fail judgment value, and stores the data. Record and confirm the end of the test in step S107, and if the test is completed, in step S108, display the test result as OK for non-defective products and NG for defective products. Is what you do. Further, the method for measuring the resolution of the image reading apparatus of the present invention is such that the black and white line pair pitch of the test chart 2 is created with a small shift from the reading pixel pitch of the image reading apparatus, and the white pattern and the read pixel In addition, the black pattern and the read pixel are matched in the main scanning direction. Using this test chart 2, an area of sufficient width is read so that the pattern and the pixel always match, and the gradation difference is calculated for each pixel of the read image of the entire area. Detect gradation difference. If the maximum gradation difference exceeds the pass / fail judgment value, the resolution test is passed.

Further, the resolution measuring method of the image reading apparatus of the present invention is such that a black and white line pattern of the test chart 2 is created by inclining a small amount, and a white pattern and a read pixel, and a black pattern and a read pixel are formed at regular intervals. Match in the sub-scanning direction. Using this test chart 2, read a vertical area sufficient to ensure that the pattern and pixel always match, calculate the tone difference for each pixel of the read image of the entire area, and Detect tonality. If the maximum tone difference exceeds the pass / fail judgment value, the resolution test is passed.

Further, in the resolution measuring method of the image reading apparatus according to the present invention, as the condition for detecting the maximum gradation difference, the gradation difference before and after the point where the maximum gradation difference candidate is detected is opposite to the detected maximum gradation difference. Have a certain level of gradation difference.

In the method for measuring the resolution of a color image of the image reading apparatus according to the present invention, a criterion is that the maximum gradation difference of each color is equal to or more than a specific value.

Further, in the method for measuring the resolution of a color image of the image reading apparatus according to the present invention, the maximum gradation difference of each color is equal to or more than an individual fixed standard value, and the sum of the maximum gradation difference of each color is the standard value of each color. Is determined to be equal to or greater than a certain value equal to or greater than the sum of Furthermore, the method of measuring the resolution of a color image of the image reading apparatus of the present invention focuses on the fact that the degree of influence on the resolution of each color is different, and when calculating the total sum of the maximum gradation difference of each color, an individual coefficient for each color is used. To calculate the sum.

In general, since the color that greatly influences the resolution is green, for example, there is a method in which the coefficient is set so that green is largest, then red, and then blue.

Further, the method for measuring the resolution of the image reading apparatus according to the present invention further comprises: scanning a black-and-white line pair pattern a plurality of times while changing the scanning position; calculating a maximum gradation difference for each scan; Out of the n data, the average value of the P maximum grayscale difference data excluding the upper N or Z and lower M data is determined.

Further, the recording medium storing the program for realizing the resolution measuring method of the image reading apparatus of the present invention is a test for making the white pattern and the read pixel coincide with each other and the black pattern and the read pixel at regular intervals of the resolution test. When reading the chart, the procedure to scan a sufficient area so that the pattern and the pixel always match, and cut out only the necessary area from the read image data, and read the entire area of the cut out image data To calculate the gradation difference for each pixel of the image and detect the maximum gradation difference, and to execute the resolution test if the maximum gradation difference exceeds the pass / fail judgment value A computer readable program.

This program is stored in various appropriate recording media such as FD and CD for recording the program.

By taking the above-described embodiment, the following operation works.

By using the test chart 2 described above, the width of the bar and the space and the size of the light receiving section of the CCD are slightly different in the main scanning direction, or the bar and the space are slightly inclined in the sub-scanning direction. Then, the contrast difference between adjacent pixels in this region changes with a certain period in the main scanning direction or the sub-scanning direction. Further, the difference in the position of the test chart 2 appears only as a horizontal displacement of the waveform, and the cycle and amplitude thereof hardly change. Therefore, regardless of the position of the test chart 2, only the maximum contrast difference is verified, and the balance between the pattern and the size of one pixel of the CCD element is lost due to the above-mentioned blurring of focus. Only when the contrast difference is small can be identified.

In this way, we focused on the contrast of the image and quantified the “visible” range. Furthermore, a test chart that was designed to facilitate the setting of the image reading device

By using 2, it is possible to perform automatic computer processing of a resolution test in which one pixel of a CCD element resolves one bar.

Furthermore, the condition for detecting the maximum gradation difference is that the gradation difference before and after the point where the maximum gradation difference candidate is detected has a certain or more gradation difference in the direction opposite to the detected maximum gradation difference. By doing so, factors such as dust and dirt on the test chart 2 in the resolution measurement can be eliminated.

Further, since the judgment standard is that the maximum gradation difference of each color is equal to or more than a specific standard value, it is possible to measure the resolution of a color image.

Furthermore, by determining the average value of a predetermined maximum gradation difference group among the maximum gradation difference groups calculated by scanning the black-and-white line pair pattern a plurality of times while changing the scanning position, the measurement accuracy is improved. Can be raised.

In addition, it can be realized by using a program for operating a computer, and since this program can be stored in various suitable recording media such as an FD or a CD for recording the program, any program can be used when necessary. It can be installed in a processing device to perform processing.

A representative embodiment according to the present invention will be specifically described with reference to FIGS. 11 to 22. FIG.

FIG. 11 is a block diagram of an embodiment of the present invention. In FIG. 11, a resolution test of the image reading device is performed by a test chart 2 shown in FIG. 12 described later, an image reading device 12 to be tested, and a measuring device 14.

The image reader 1 2 (reading means 3) controls the operation of the light source lamp 22, the CCD element 23, and the reading moving unit 24 by the arithmetic control unit 21 based on the instruction from the measuring device 14. Then, the read image data of the test chart 2 is transferred to the measuring device 14.

The measuring device 14 is controlled by the arithmetic and control unit 41 and exchanges data with the image reading device 12 via the driver program 42, and the received image data is arithmetically controlled. Processed by the measurement control program 43 according to the instruction of the unit 41. The display unit 46 displays necessary data results in the resolution test. The storage unit 47 stores test result data and the like.

The measurement control program 43 includes a data analysis unit 44 and a determination unit 45. The measurement control program 4 3 (cutout means 4) cuts out only necessary portions from the image data read by the image reading device 12. The data analysis unit 44 (analysis means 5) calculates a gradation difference for each pixel of the read image of the entire region of the cut image data, and calculates a maximum gradation difference. The judging section 45 (judgment means 6) judges that the resolution test has passed if the maximum gradation difference exceeds the pass / fail judgment value for various pass / fail judgment values required for the resolution test set in advance. If the value does not exceed the pass / fail judgment value, the resolution test is rejected.

FIG. 12 is an explanatory diagram of an embodiment of the present invention, and illustrates a main part of the test chart 2 described above. In FIG. 12 (a), the test chart 2 has a large number of black bars and a large number of white spaces, and the pattern pitch of a black-and-white line pair composed of the black bars and the white spaces is mainly shown. This is set slightly larger than the pitch of a plurality of CCD elements arranged side by side in the scanning direction. For example, 11〃m bars and spaces required for the measurement of 2400 dpi are set to 12〃m, and several hundreds of these are arranged.

In FIG. 12 (b), test chart 2 has a pattern pitch of a black and white line pair composed of a number of black bars and a number of white spaces, and the black bars and the white spaces. The pitch is set slightly smaller than the pitch of a plurality of CCD elements juxtaposed in the main scanning direction. For example, 11〃m bars and spaces required for the measurement of 2400 dpi are set to 10〃m, and several hundreds of them are arranged.

The test chart 2 shown in Fig. 12 (a) and Fig. 12 (b) is produced by shifting the pitch of one pixel of the CCD element of the image reading device to be tested by a small amount so that the test chart 2 can be obtained. In the positional relationship between the CCD and the CCD element, the white pattern and one pixel of the CCD element, and the black pattern and one pixel of the CCD element coincide in the main scanning direction at regular intervals. In FIG. 12 (c), test chart 2 has a number of black bars and a number of white spaces, and the pattern pitch of a black and white line pair composed of the black bars and the white spaces is as follows. Set the same as the pitch of a plurality of CCD elements juxtaposed in the main scanning direction. Further, the black and white line pairs are formed with a slight inclination with respect to the sub-scanning direction, and several hundred lines are arranged.

Test chart 2 shown in Fig. 12 (c) shows that the white pattern and one pixel of the CCD element, and the black pattern and one pixel of the CCD element are sub-patterns at regular intervals in the positional relationship between the test chart 2 and the CCD element. It becomes coincident in the scanning direction.

FIG. 15 is an explanatory view of an embodiment of the present invention. FIG. 15 shows a state in which the pattern formed on the test chart 2 is read by the pixel reading device 13 capable of reading the test object one pixel at a time, and the measuring device 14 performs resolution measurement processing.

In FIG. 15, the CCD output indicates the output of each pixel of the CCD element when one line of the pattern of the test chart 2 is read. The gradation difference indicates a level difference between adjacent pixels of the CCD element. In other words, you can see clearly if the mountain is high. Further, the pattern is a pattern image when the pattern formed on the test chart 2 is read.

As described above, by reading the pattern of the test chart 2 shown in FIG. 12 described above, the contrast difference (gradation difference) between one pixel of the adjacent CCD element in the read area is determined in the main scanning direction or in the main scanning direction. It changes with a constant period in the sub-scanning direction. In addition, the difference in the position of the test chart 2 appears as a horizontal shift of the waveform, and its cycle and amplitude hardly change. Therefore, regardless of the position of test chart 2, only the maximum contrast difference is verified, and the balance between the pattern and the size of one pixel of the CCD element is lost due to the above-mentioned blurring of the focus and the contrast difference is small. Only cases can be identified.

In this way, focusing on the contrast of the image, the “visible” range was quantified. In addition, the use of the test chart 2 that facilitates setting on the image reading device to be tested facilitates the automatic computer processing of the resolution test in which one pixel of the CCD element resolves one bar. can do.

FIG. 16 shows a flowchart of an embodiment of the present invention. In Fig. 16, resolution An outline of the processing procedure of the degree measurement method will be described. The same reference numerals as those shown in FIG. 11 are used.

In step SI 11, the judge sets the test chart 2 at a predetermined position of the image reading device 12 to be tested and instructs the reading.

In step SI 12, the image reading device 12 drives the light source lamp 22, the CCD element 23, and the reading moving section 24 to read the entire area of the test chart 2. In step S113, the read image data of the test chart 2 is transferred to the measuring device 14.

In step S114, the measurement device 14 receives the image data, and in step S115, the measurement control program 43 cuts out a measurement target portion from the range of the resolution pattern.

In step S116, the data analysis unit 44 of the measurement control program 43 calculates the gradation difference for each pixel of the read image of the entire area of the cut image data, and in step S117, , Detect maximum gradation difference.

In step S118, the judgment unit 45 of the measurement control program 43 compares the pass / fail judgment value set in advance with the maximum gradation difference, and when the maximum gradation difference exceeds the pass / fail judgment value. Is determined.

If the maximum gradation difference does not exceed the pass / fail judgment value, in step SI 19, the image reading device 12 is determined to be defective because it does not have the resolution of the basic specification. On the other hand, if the maximum gradation difference exceeds the pass / fail judgment value, in step S120, the image reading device 12 is determined to be non-defective because it has the resolution of the basic specification.

In step S121, the measurement result data is recorded in the storage unit 47, and in step S122, it is determined whether or not the resolution measurement has been completed, and if it has been completed, the test result is displayed in step S123. Is displayed and the process ends. If not, return to step S115.

The details of the resolution measurement processing procedure of the measurement device 14 will be described below.

FIG. 17 shows a flowchart of an embodiment of the invention. FIG. 17 shows the processing procedure of the measurement control program 43 in measuring the resolution of a monochrome image.

In step S131, the measurement cut out from the range of the resolution pattern Verify whether there is an abnormal pixel in the target part. If an abnormal pixel is detected, it is stored. That is, as shown in FIG. 13, the gradation data is examined for each pixel of the CCD element, and if a pixel that should read a black pattern does not read a black pattern, or a white pattern should be read. If the pixel to be read does not read the white pattern, store the number of that pixel. In this example, the pixel E3, the pixel E4, and the pixel E5, or the pixel E22, the pixel E23, and the pixel E24 correspond. This indicates that the pattern formed on the test chart 2 is not correct and does not form a pattern due to factors such as dust and dirt. Therefore, in the resolution measurement, the location is excluded from the measurement target.

In step S132, the number of pixels in the measurement area corresponding to the measurement target portion cut out from the range of the resolution pattern is set to count. For example, in the case of a measurement area as shown in FIG. 13, the pixel number counter is set to 43.

In step S133, an initial value of the maximum gradation difference is set and stored.

In step S134, the first measurement pixel is set to count. For example, E 0 in FIG. 13 is set.

In step S135, the next measurement pixel is set to count. For example, E1 in FIG. 13 is set.

In step S136, it is determined whether the measurement pixel is a normal pixel. That is, the pixel stored in step S1331 is an abnormal pixel, and if it is any other pixel, the process proceeds to step S137. If it is an abnormal pixel, the process returns to step S135.

In step S137, a gradation difference from the gradation data of an adjacent previously measured pixel is calculated, and it is determined whether the difference is larger than the currently stored maximum gradation difference. If the difference is larger than the currently stored maximum gradation difference, the flow advances to step S138. If it is smaller than the currently stored maximum gradation difference, the flow advances to step S139.

The judgment is based on the following equation.

a b s (Ε „-Ε„-ι)> = M a x_D i f f

In the above formula, abs is an absolute value, E _n gradation data of the measuring pixel, E _n> gradation data of the pixel previously measured adjacent, M ax- D iff outermost Daikaicho currently stored The difference,. In step S138, the maximum gradation difference is stored.

In step S139, it is determined whether the number of pixels in the previously set measurement area has been measured. That is, it is determined whether the number of pixels set in the counter has been reached. If all the pixels in the measurement area have been measured, the process proceeds to step S140. If all the pixels in the measurement area have not been measured, the process returns to step S135.

In step S140, a predetermined pass / fail judgment value is compared with the stored maximum gradation difference to determine whether the maximum gradation difference exceeds the pass / fail judgment value. In step 1, the test result is displayed on the display unit, and the process ends.

In other words, by the steps S 13 1 and S 13 36, as a condition of the maximum gradation difference detection, the gradation difference before and after the point where the maximum gradation difference candidate is detected is set to the detected maximum gradation difference. By having a certain level of gradation difference in the reverse direction, it is possible to eliminate factors such as dust and dirt on the test chart in the resolution measurement.

FIG. 18 shows a flowchart of an embodiment of the invention. FIG. 18 shows the processing procedure of the measurement control program 43 in measuring the resolution of a color image. It should be noted that the processing procedures corresponding to step S131 and step S136 shown in FIG. 17 are omitted.

In step S151, the number of pixels in the measurement area corresponding to the measurement target portion cut out from the range of the resolution pattern is set in the counter. For example, in the case of a measurement area as shown in FIG. 13, the pixel number counter is set to 43.

In step S152, an initial value of the maximum gradation difference of red is set and stored. In step S153, an initial value of the maximum gradation difference of green is set and stored. In step S154, an initial value of the maximum gray level difference of blue is set and stored. In step S155, the first measurement pixel is set to count. For example, E 0 in FIG. 13 is set. One pixel of the CCD element has three gradation data of red, green, and blue.

In step S156, the next measurement pixel is set to count. For example, E1 in FIG. 13 is set.

In step S157, the gradation difference between the previously measured pixel and the red gradation data of the adjacent pixel is calculated, and it is determined whether the difference is larger than the currently stored maximum gradation difference of red. . If it is larger than the currently stored maximum gradation difference of red, the process proceeds to step S158. If the difference is smaller than the maximum gradation difference of red, the process proceeds to step S159.

The judgment is based on the following equation.

abs (R _n -R „-i)> = Diff-1 Rma x

In the above equation, abs is the absolute value, R „is the red gradation data of the measured pixel, R _n- , is the red gradation data of the adjacent previously measured pixel, and D ff — R max is currently stored. Is the maximum gradation difference of the red color.

In step S158, the maximum gradation difference of red is stored.

In step S159, the difference between the previously measured green gradation data of the pixel and the previously measured pixel is calculated, and it is determined whether the difference is larger than the currently stored maximum gradation difference of green. If it is larger than the currently stored maximum gradation difference of green, the process proceeds to step S160. If the difference is smaller than the maximum gradation difference of green, the process proceeds to step S161.

The judgment is based on the following equation.

abs (G _n -G „-i)> = D iff _Gma x

In the above equation, abs is the absolute value, _Gn is the green gradation data of the measured pixel, is the green gradation data of the adjacent previously measured pixel, and Diff-Gmax is the currently stored green maximum. The gradation difference is

In step S160, the maximum gray level difference of green is stored.

In step S161, a gradation difference between the previously measured pixel and the blue gradation data of the previously measured pixel is calculated, and it is determined whether the currently stored blue gradation data is larger than the maximum gradation difference of blue. If it is larger than the currently stored maximum gray level difference of blue, the process proceeds to step S162. If the difference is smaller than the maximum gray level difference of the blue color, the flow advances to step S163.

The judgment is based on the following equation.

ab s (Β „-Β _η -ι)> = D iff _Bma x

In the above formula, abs is an absolute value, B „is the blue gradation data of the measured pixel, B _n —! Is the blue gradation data of the adjacent pixel measured earlier, and D ff — Bmax is the current value. This is the maximum difference in gray level of blue that is remembered.

In step S162, the maximum gray level difference of blue is stored.

In step S163, the number of pixels in the measurement area previously measured is all measured. Is determined. That is, it is determined whether the number of pixels set in the counter has been reached. If all the pixels in the measurement area have been measured, the flow advances to step S164. If all the pixels in the measurement area have not been measured, the process returns to step S156.

In step S164, the pass / fail judgment value set in advance is compared with the stored maximum gradation difference to determine whether or not the maximum gradation difference exceeds the pass / fail judgment value. In step 5, the test result is displayed on the display unit, and the process ends.

The details of step S164 will be described later. Also, in the omitted processing procedure corresponding to steps S 13 1 and S 13 36 shown in FIG. 17, the detection of the abnormal pixel is executed prior to step S 15 1 . The determination as to whether the measurement pixel is a normal pixel is performed between step S156 and step S157.

Hereinafter, the details of the aforementioned step S166 will be described.

FIG. 19 shows a flowchart of an embodiment of the present invention. FIG. 19 uses the judgment criterion that the maximum gradation difference of each color of the color image is equal to or more than a specific value.

In step S166a, it is determined whether the maximum gradation difference of red is larger than the standard value for red component. If the maximum gradation difference of red is larger than the red component standard value, the flow advances to step S164b. If the maximum gradation difference of red is smaller than the standard value for red component, the process proceeds to step S164d.

The judgment is based on the following equation.

D i f ί— Rmax> = R t o 1

In the above equation, Dif-Rmax is the maximum gradation difference of red, and Rto1 is the standard value for the red component.

In step S164b, it is determined whether the maximum gradation difference of green is larger than the standard value for green component. If the green maximum gradation difference is larger than the green component standard value, the flow advances to step S164c. If the maximum gradation difference of green is smaller than the standard value for green component, the process proceeds to step S164d.

The judgment is based on the following equation.

D iff _Gm ax> = G to 1 In the above equation, Diff-Gmax is the maximum gradation difference of green, and G to 1 is the standard value for the green component.

In step S164c, it is determined whether the maximum gray level difference of blue is larger than the standard value for blue component. If the maximum gradation difference of blue is larger than the blue component standard value, the flow advances to step S164e. If the maximum gray level difference of blue is smaller than the blue component standard value, the flow advances to step S164d.

The judgment is based on the following equation.

D i f f _B m ax> = B t o 1

In the above equation, Dif-Bmax is the maximum gray level difference of blue, and Bto1 is the standard value for the blue component.

In step S164d, it is determined that there is no resolution and is determined to be defective. Also, in step S164e, it is determined that there is a resolution, and a non-defective product is determined. Then, the process ends.

FIG. 20 shows a flowchart of an embodiment of the present invention. Fig. 20 shows that the maximum gradation difference for each color of a color image is equal to or greater than a specific standard value for each color, and that the sum of the maximum gradation differences for each color is equal to or greater than the three-color total standard value. This is used as a criterion. In step S164h, it is determined whether the maximum gradation difference of red is larger than the standard value for red component. If the maximum tone difference of red is larger than the red component standard value, the flow advances to step S164i. If the maximum gradation difference of red is smaller than the standard value for red component, the flow advances to step S1661.

In step S164i, it is determined whether the maximum gradation difference of green is larger than the standard value for green component. If the maximum gradation difference of green is larger than the green component standard value, the flow advances to step S164j. If the green maximum gradation difference is smaller than the green component standard value, the flow advances to step S16641.

In step S164j, it is determined whether the maximum gray level difference of blue is larger than the standard value for blue component. If the maximum gradation difference of blue is larger than the blue component standard value, the flow advances to step S164k. If the maximum gradation difference of blue is smaller than the standard value for blue component, the process proceeds to step S1641.

Steps S164h, S164i and S164] Therefore, the equation for determining whether the maximum gradation difference of each color is larger than the standard value for each color component is as follows: Step S 164 a, Step S 1 64 b and Step S 1 64 c shown in FIG. Equivalent, and description is omitted.

In step S164k, it is determined whether or not the total of the maximum gradation differences of the three colors red, green and blue is larger than the total standard value of the three colors red, green and blue. If the total of the maximum gradation differences of the three colors is larger than the total standard value of the three colors, the process proceeds to step S164m. If the total of the maximum gradation differences of the three colors is smaller than the total standard value of the three colors, go to step S1641 ο

The judgment is based on the following equation.

D i f f— Rmax x D i f f _Gma x + D i f f _Bma x> = RGB t o 1

In the above formula, Diff—Rmax is the maximum gradation difference of red, Diff_Gmax is the maximum gradation difference of green, Diff—Bmax is the maximum gradation difference of blue, and RGB to 1 is the standard value of three colors. ,.

In step S1641, it is determined that there is no resolution and is determined to be defective. At step S164m, it is determined that there is a resolution, and is determined to be non-defective. Then, the process ends.

FIG. 21 shows a flowchart of an embodiment of the present invention. FIG. 21 is a diagram for calculating the total sum by multiplying each color by an individual coefficient when calculating the total sum of the maximum gradation differences of each color of the color image.

In step S164r, it is determined whether the maximum gradation difference of red is larger than the standard value for red component. If the maximum gradation difference of red is larger than the standard value for red component, the process proceeds to step S164s. When the maximum gradation difference of red is smaller than the standard value for red component, the process proceeds to step S164V.

In step S164s, it is determined whether the maximum gradation difference of green is larger than the standard value for green component. If the green maximum gradation difference is larger than the green component standard value, the flow advances to step S164t. If the green maximum gradation difference is smaller than the green component standard value, the flow advances to step S164V.

In step S164t, the maximum gradation difference of blue is larger than the standard value for blue component. Is determined. If the maximum gradation difference of blue is larger than the blue component standard value, the flow advances to step S164u. If the maximum gray level difference of blue is smaller than the blue component standard value, the flow advances to step S164V.

In step S164r, step S164s, and step S164t, the equation for determining whether the maximum gradation difference of each color is larger than the standard value for each color component is shown in FIG. 19 described above. Steps S164a, S164b, and S164c shown are the same as those described above, and description thereof is omitted.

In step S1 64u, the total of the maximum gradation differences of the three colors multiplied by the component coefficients for each color set to red, green, and blue is larger than the total standard value of the three colors of red, green, and blue. Is determined. If the total of the maximum gradation differences of the three colors is larger than the total standard value of the three colors, the process proceeds to step S164W. When the total of the maximum gradation differences of the three colors is smaller than the total standard value of the three colors, the process proceeds to step S164V.

The judgment is based on the following equation.

D iff one Rmaxxk _R + D iff _Gmaxxk _G + D iff _Bma xxk _B > = RGB to 1

In the above equation, Diff—Rmax is the maximum gradation difference of red, Diff—Gmax is the maximum gradation difference of green, Diff—Bmax is the maximum gradation difference of blue, k _R is the coefficient for the red component, k _G is the coefficient for the green component, k _B is the coefficient for the blue component, and RGB t 01 is the three-color comprehensive standard value.

In general, since the individual color component coefficients set for each color generally have the effect of increasing the resolution in green, the size of the color component coefficient is set to the largest for the green component coefficient, and then to red. Set the coefficient for the component and then the coefficient for the blue component. For example, the coefficient for the green component (k _G ) = 2.0, the coefficient for the red component (k _R ) = 1.5, and the coefficient for the blue component (k _B ) = 1.0.

In step S164V, it is determined that there is no resolution and is determined to be defective. Also, in step S164w, it is determined that there is a resolution and a non-defective item is determined. Then, the process ends.

18 to 21, it is possible to measure the resolution of a blank image. Next, the main processing procedure of another resolution measuring method will be described.

FIG. 22 shows a flowchart of an embodiment of the present invention. Fig. 22 shows that the black-and-white line pair pattern is scanned multiple times while changing the scanning position, the maximum gradation difference is calculated for each scan, and the upper N and lower M of the maximum gradation difference group are calculated. The following shows the processing procedure of the measurement control program 43, with the average value of the P maximum gradation difference groups excluding as the judgment target. Note that the processing procedures and the like corresponding to steps S 13 1 and S 13 36 shown in FIG. 17 are omitted.

In step S 171, for example, as shown in FIG. 14, the initial values of the maximum gradation difference of each scanning line (l to n) to be measured are sequentially set and stored.

In step S172, the first scan line is set to count. For example, Line 1 in FIG. 14 is set.

In step S173, the maximum gradation difference is stored from among the first scanning lines. In other words, it sequentially calculates the gradation difference between the previously measured pixel and the previously measured pixel, and determines whether the difference is larger than the currently stored maximum gradation difference. If it is larger than the difference, the maximum gradation difference is stored.

The judgment is based on the following equation.

abs (E _m . „-E _m -i.„)> = M a x_D iff _n

In the above equation, abs is the absolute value, E _m .n is the gradation data of the measured pixel, E _m —,. _N is the gradation data of the adjacent previously measured pixel, and Max — Diff „is currently stored. Is the maximum gradation difference of the scanning line.

In step S174, the next scanning line is set in the counter.

In step S175, the maximum gradation difference from the scanning lines is stored. In other words, it sequentially calculates the gradation difference between the previously measured pixels and the gradation data of the adjacent pixels, determines whether the difference is larger than the currently stored maximum gradation difference, and determines the currently stored maximum gradation difference. If the difference is larger than the difference, the maximum gradation difference is stored. The judgment is the same as the above equation. In step S176, it is determined whether or not all the measurement has been performed up to the last scan line of each scan line (1 to! 1) to be measured previously set. If all have been measured, proceed to step S177. If all have not been measured, the process returns to step S174.

In step S177, the maximum gradation difference of each scanning line is arranged in ascending order. Then, out of the n pieces of the maximum gradation difference data, the upper N pieces and the lower M pieces are excluded from the test. Note that the upper N numbers are 0 = N <= n_1. In addition, the lower M numbers are 0 <= M <= n-1. However, it is assumed that 0 <= N + M <= n—1.

In step S178, the average value of the maximum gradation difference group is calculated and stored. The average value of the maximum gradation difference group is obtained by dividing the sum of the maximum gradation difference groups by the total number of the maximum gradation difference groups. That is, the average value of the maximum gradation difference group is given by the following equation.

n -N

D i f f = ∑ Ma x_D i f f; (n-N-M)

i In the above equation, Diff _AVC is the average value of the maximum gradation difference group, ∑Ma X—Diff _; (i is an integer from M + 1 to n—N) is the sum of the maximum gradation difference groups, n—N — M is the total number of the maximum difference groups.

In step S179, the pass / fail judgment value set in advance is compared with the stored average value of the maximum gradation difference group to determine whether the average value of the maximum gradation difference group exceeds the pass / fail judgment value. Then, in step S180, the test result is displayed on the display unit, and the process ends.

This makes it possible to improve the measurement accuracy by scanning the black and white line pair pattern a plurality of times while changing the scanning position.

Further, the resolution measuring process of the image reading apparatus of the present invention is realized by using a program for operating a computer. This program is stored in various suitable recording media such as FDs and CDs for self-recording.

The resolution measuring method of the image reading apparatus of the present invention focuses on the contrast of the image, quantifies the “visible” range, and furthermore, considers a test chart that considers the ease of setting the image reading apparatus. By using this, automatic computer processing of a resolution test in which one pixel of a CCD element resolves one bar can be performed, and therefore, an efficient production system can be adopted. Further, when measuring the resolution of the image reading device, it is possible to eliminate factors such as dust and dirt on the test chart. Also, Furthermore, it is possible to measure the resolution of a color image. Furthermore, the scanning accuracy can be improved by scanning the monochrome line pattern a plurality of times while changing the scanning position. In addition, the program can be realized by using a program for operating a computer, and this program can be stored in various appropriate recording media such as an FD and a CD for recording the program. The device can be installed and processed. Industrial applicability

According to the image noise measuring method for an image reading device of the present invention, the image reading device is caused to read a test chart having a predetermined reading area, and a value calculated from the result exceeds a predetermined numerical value range. In this case, since the image noise is detected, a unique criterion for detecting the image noise can be provided, so that the image noise can be reliably measured without relying on the visual check of the worker. be able to. Further, the method for measuring image noise of the image reading apparatus of the present invention can be realized by using a program for operating such a computer, and the program can be stored in various recording media. A desired measuring device can perform the measuring process.

Further, the method for measuring the resolution of the image reading apparatus of the present invention is to read a test chart created by shifting the pitch of the black and white line pair pattern by a small amount from the reading pixel pitch of the image reading apparatus, and read the maximum gradation calculated from the result If the difference exceeds the pass / fail judgment value, a resolution test is passed, and the resolution at which one pixel of the CCD element resolves one bar can be automatically calculated. It also eliminates factors such as dust and dirt on the test chart, making it possible to measure the resolution of an empty image. Further, the method for measuring the resolution of the image reading apparatus of the present invention can be realized using a program for operating such a computer, and the program can be stored in various recording media. A desired measuring device can perform the measuring process.

Claims

The scope of the claims

1. In an image noise measuring method for an image reading device that connects to a host device and provides image data to the host device,

The image reading device is caused to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and a standard deviation value of optical density of all pixels in the individual measurement area is obtained. Calculate,

When the standard deviation value deviates beyond a predetermined numerical range, the image reading device detects the image noise by detecting the standard deviation value.

An image noise measuring method for an image reading apparatus, comprising:

2. A method for measuring image noise of an image reading device that is connected to a host device and provides image data to the host device.

The image reading device is made to read a single uniform density reading area or a plurality of uniform density reading areas at different density levels. The average density of each vertical line, which is the average value of the output sequentially read in the scanning direction, is calculated,

When the average density of a specific vertical line deviates from the average density of each vertical line in the vicinity or the average density of the entire individual measurement area beyond a predetermined numerical range, the vertical line is set as a noise line. Is determined, and the image reading apparatus detects an image noise.

An image noise measuring method for an image reading apparatus, comprising:

3. In connection with a host device, an image reading device that provides image data to the host device has an image noise measuring method.

The image reading device was made to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and read in the individual measurement areas in the main scanning direction. I is the average density of each horizontal line, which is the average value of the output,

The average density of a specific horizontal line deviates from the average density of each horizontal line in the vicinity or exceeds a predetermined numerical value range with respect to the average density of the entire individual measurement area. In this case, the horizontal line is determined to be a noise line, and the image reading device detects an image noise.

An image noise measuring method for an image reading apparatus, comprising:

4. An image noise measuring method for an image reading apparatus which is connected to a host apparatus and provides image data to the host apparatus,

The image reading device is caused to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and the individual CCD elements are sequentially arranged in the sub-scanning direction in the individual measurement areas. Calculate the average density of each vertical line, which is the average value of the read output,

When the average density of a specific vertical line deviates from a predetermined numerical value range with respect to the average density of an adjacent vertical line, the vertical line is determined to be a noise line, and image noise is reduced by the image reading device. It is detected

An image noise measuring method for an image reading apparatus, comprising:

5. In the image noise measuring method for an image reading device which is connected to a host device and provides image data to the host device,

The image reading device was made to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and read in the individual measurement areas in the main scanning direction. Calculate the average density of each horizontal line, which is the average value of the output,

When the average density of a specific horizontal line deviates beyond a predetermined numerical value range with respect to the average density of the adjacent horizontal line, the horizontal line is determined to be a noise line, and image noise is reduced by the image reading device. It is detected

An image noise measuring method for an image reading apparatus, comprising:

6. A recording medium which is connected to a host device and stores a program for realizing control of a measuring device for measuring image noise of an image reading device for providing image data to the host device,

The image reading device is caused to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and a standard deviation value of optical density of all pixels in the individual measurement area is obtained. Calculation procedure, Storing a program for causing a computer to execute a procedure for reporting that image noise has been detected in the image reading device when the standard deviation value deviates beyond a predetermined numerical range.

A computer-readable recording medium characterized by the above-mentioned.

7. A recording medium for connecting to a host device and storing a program for controlling a measuring device for measuring image noise of an image reading device for providing image data to the host device,

The image reading device is caused to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and the individual CCD elements are sequentially arranged in the sub-scanning direction in the individual measurement areas. Calculating the average density of each vertical line, which is the average value of the read output;

When the average density of a specific vertical line deviates from the average density of each vertical line in the vicinity or the average density of the entire individual measurement area beyond a predetermined numerical range, the vertical line is set as a noise line. And a procedure for causing the computer to execute the procedure of reporting that the image reading apparatus has detected image noise.

A computer-readable recording medium characterized by the above-mentioned.

8. A recording medium which is connected to a host device and stores a program for realizing control of a measuring device for measuring image noise of an image reading device for providing image data to the host device,

The image reading device is made to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and the average value of outputs read in the main scanning direction in the individual measurement areas is obtained. Calculating the average density for each vertical line

If the average density of a specific horizontal line deviates from the average density of the horizontal line in the vicinity or the average density of the entire individual measurement area beyond a predetermined numerical range, the vertical line is regarded as a noise line. And a program for causing a computer to execute a procedure of determining and reporting that an image noise has been detected in the image reading apparatus. A recording medium readable by a computer.

9. A recording medium which is connected to a host device and stores a program for realizing control of a measuring device for measuring image noise of an image reading device for providing image data to the host device,

If the average density of each specific vertical line deviates from the average density of the adjacent vertical line beyond a predetermined numerical range, the vertical line is determined to be a noise line and the image is read by the image reading device. Detecting noise detection and storing the program to run on your computer

A computer-readable recording medium characterized by the above-mentioned.

10. A recording medium that stores a program for controlling a measuring device that measures image noise, of an image reading device that is connected to a host device and provides image data to the host device,

The image reading device is made to read a single uniform density reading area or a plurality of uniform density reading areas having different density levels, and the average value of outputs read in the main scanning direction in the individual measurement areas is obtained. Calculating the average density for each horizontal line,

If the average density of a specific horizontal line deviates beyond a predetermined numerical value range with respect to the average density of an adjacent horizontal line, the vertical line is determined to be a noise line, and image noise is reduced by the image reading device. Storing a program that causes the computer to execute the procedure for reporting the detection

A computer-readable recording medium characterized by the above-mentioned.

1 1. Create a black-and-white line pair pattern with a small shift from the read pixel pitch of the image reading device, or create a black-and-white line pair pattern with a small inclination and read it as a white pattern at regular intervals of the resolution test. A test chart in which the pixels and the black pattern and the read pixels match in the main scanning direction or the sub-scanning direction, Read the test chart. Reading means for reading a width or a vertical area which is sufficient to ensure that a turn and a pixel always coincide with each other;

Cutting means for cutting out only necessary portions of the image data read by the reading means,

Analysis means for calculating a gradation difference for each pixel of a read image of the entire area of the cut image data and detecting a maximum gradation difference;

If the maximum gradation difference exceeds the pass / fail judgment value, the resolution test is passed.

A resolution measuring device for an image reading device.

1 2. The pitch of the black-and-white line pair pattern of the test chart is slightly shifted from the pixel pitch of the image reading device, and the white pixels, the read pixels, and the black pixels at regular intervals. Use a test chart created so that the reading pixels match the evening,

No ,. An area of sufficient width is read so that there is always a point where the turn and the pixel always match, the tone difference is calculated for each pixel of the read image of the entire area, the maximum tone difference is detected, and the maximum tone difference is detected. A resolution measurement method for an image reading apparatus, wherein a resolution test is passed when the value exceeds a pass / fail judgment value.

1 3. Use a test chart created by tilting the black-and-white line pair pattern of the test chart by a small amount so that the white pattern and the read pixel and the black pattern and the read pixel match at regular intervals.

A sufficient vertical area is read so that there is always a point where the pattern and the pixel match, and the maximum gray level difference is detected by calculating the gray level difference for each pixel of the read image of the entire area. A resolution measurement method for an image reading apparatus, wherein a resolution test is passed when the value exceeds a pass / fail judgment value.

14. The detection of the maximum gradation difference is that the gradation difference before and after the point where the maximum gradation difference candidate is detected has a certain or more gradation difference in a direction opposite to the detected maximum gradation difference. Condition

14. The method for measuring the resolution of an image reading device according to claim 12, wherein:

15. The maximum gradation difference of each color of the color image is more than Is based on

16. The maximum gradation difference for each color of a color image is equal to or greater than a specific standard value for each color, and the sum of the maximum gradation differences for each color is equal to or greater than a specific value for each color. Use the judgment as a criterion

16. The method for measuring the resolution of an image reading device according to claim 15, wherein:

1 7. When calculating the sum of the maximum gradation differences of each color of the color image, calculate the sum by multiplying each color by an individual coefficient.

18 8. Scan the black-and-white line pair pattern a plurality of times while changing the scanning position, calculate the maximum gradation difference for each scan, and select the upper N or Z and lower N of the n maximum gradation difference data. IV [The average value of the P maximum gradation difference data excluding P is determined.

14. The method for measuring the resolution of an image reading device according to claim 12, wherein the resolution is measured.

19. A recording medium that stores a program for controlling a measuring device that measures a resolution of an image reading device that connects to a host device and provides image data to the host device,

When reading a test chart in which the white pattern and the read pixel and the black pattern and the read pixel coincide with each other at regular intervals of the resolution test, a sufficient area must be provided so that the pattern and the pixel always coincide. Reading procedure,

The hand that cuts out only the necessary portions of the scanned image data and calculates the tone difference for each pixel of the read image of the entire area of the cut image data to detect the maximum tone difference) ,

If the maximum gradation difference exceeds the pass / fail judgment value, a procedure to pass the resolution test is executed.

A computer-readable recording medium characterized by the above-mentioned.